Refining of long chain aliphatic alcohols



UNITED STATES Patented July 21, 1953 g 2,646,394? I REFINING OF'LONG QHAINALIPHATIQ: 1

w a nLoonoLs Ralph V. Green=andErnest P. Jensen, Charleston, W. Va., assignors to E. I. du Pont d'eNemou'rs ,& Company, -Wilmington, DelL, a corporation: of Delaware" f No Drawing. Application D ecember27,.l 9'5fl,

Serial No. 203,020

This invention relates to: aprocess for recovering long chain aliphatic alcohols from reaction mixtures containing them, and more particularly .relates to the treatment of reaction-products from the hydrogenation of long chain fatty acids and their esters to increase the-amount of alcohols recoverable therefrom.

@ The produ-ctionof long. chain alcohols in recent years has beenfiby andlarge, via the hydrogenation of corresponding acids, esters 'and/ or 'glycerides, theser'eactions being conductedgenerally in the presence of a suitable hydrogenation catalyst, such as nickel, cobalt or the copper chromite catalysts of the Lazier U. S.' Patents 1,964,000" and 2,000,880. Generally the hydro- "genated'product. which contains a" multiplicity of byproducts,isudrawnqfrom the converter through acooler before reducingthehydrogenation pressure and the product filtereduntil free of "solid catalyst.

Theffiltered product is then .3

,7 Claims. (o1; ;202-5-7) the catalysts are dissolved in the reaction mixture. It has been found-that" even though but minute quantities of the dissolved metals arev present, that'is as'little as 200 to 500p. pymi,

subjected to.variousrefiningstepsto recover. the

- alcohols produced by the hydrogenation Yields of long chain aliphatic. alcohols from. the hydrogenated fatty oils have varied over a ide range for no apparent reason and asa, consequencano uniformity in the amount of. the alcohols recovered was assured fromany given amount of the fatty oils hydrogenated.

.An object of the present invention is to provide .bulk of the metal catalysts employed during catainordinately low recovery of the alcohols" present results. By,"for example, precipitating thedissolved metals by oxalic acid" or. other suitable precipitating agent,*filtering out the precipitated 'metal salts and then subjecting the metal-free solution .to distillation, a surprisingly greater amount of the higher fatty alcohols can 'b'e recovered from the reaction mixture, providing'the dissolved metal is reduced to 50 p'xp. m. and preferably 10 p. p. m. or less.

Generally the hydrogenation; of long-' chai'n fatty acids, such as oleic acid, coconutoil acids,

palmitic acid, lauric acid, stearic acid, oleic acid,

and such oils as China-wood,,corn,, peanut,rcastor oils and other high molecular weight vegetable and animaloil acids, together with esters of these acids, isconducted in the presence of metal oxide and metal salt catalysts. A number of. catalysts are used forthis purpose, such, for example, as the heavy metals andtheir oxides, and'moreparticularly the salts and theoxi'des 'ofzi'nc', nickel,

Qaprocess forimprovingthe recovery-of long chain copper, cadmium and chromium.outstanding aliphatic alcohols from; reaction mixtures concatalysts for the reaction beingthe copper chro- ,taining them. Another object is to provide a mite catalysts of the Lazier patents supra. The process for improving the yields of long chain Lazier catalysts are principallymixturesofcop-. aliphatic alcohols; from reaction mixtures conper oxide and chromic oxide which are considered taining them by removing from themixtures mito be copper chromites. These catalysts, and ,nute amounts-of dissolved metals .prior to-recovoth r suita le hydroge ation ata ystsgar fi ccry of the alcohols. Yetanother object is to protive for hydrogenating the aforesaid acids and vide a process for precipitating copper from the esters at temperatures ranging between 240 and reaction product obtained'by hydrogenating fatty 400 C. and under pressures ranging from 300 to oils and/ or acids in the presence: of; copper '5000 lbs/sq. inch or higher. g

1 ;chromite catalysts and thereafterrecovering the The invention of the instantcase: is principally longchain fatty alcoholstherefrom byfractional directed to the treatmentof the. filtered crude distillation. Otherobjects and advantages of the reaction products, i. e., the filtered reaction mix- .invention will appear hereinafter. ture from hydrogenation, prior to recoveryof the In accord with the invention, crude reaction lon ch in liphatic alcohols present therein. vIt mixtures obtained bythe' catalytic reduction of has been found that'thepresence of the dissolved ,fatty oils. and/or acids are'subjected, after-remetals, and more particularly: dissolvedcopper moval of catalysts or metal, reducing agents by usually found combined with the fatty acid and/or filtration, to treatment-for removal of dissolved ester, which has been subjected to hydrogenation, metals, and the substantially metal-free crude I inhibits the recovery of the long chain aliphatic product subjected to distillation for the recovery alcohols. Without the separation of the dissolved of the high molecular weight alcoholslcontained copper, in many instances,zno long-chain alcohol therein. .The filtration of metallic catalystaprior can be recovered, While from the same hydrovto separating the dissolved metals, removes the genated oil excellent yields of the long chain V 515 aliphatic alcohols can beobtained,-providing sub.-'

Due to the high of'the catalyst present.

stantially all of the dissolved metals are removed prior to the recovery step.

The examples provide particular embodiments of the invention in which parts are by weight unless otherwise indicated. 1

Example 1. Into a pressure resisting autoclave of about 400 gallon capacity, there is pumped 1900 lbs. of palmitic acid, together with about 100 lbs. of a copper chromite catalyst having the formula 9CuOCuCrzO4. The autoclave and contents are heated to a temperature between 200 C. to 300 C. and hydrogen introduced until a pressure between 4500 and 4800 lbs/sq. inch is obtained. 'As the hydrogen is consumed, additional hydrogen is introduced to maintain the pressure at approximately 4500 lbs/sq. inch. When no more hydrogen is consumed the charge is cooled to about 200 C. and discharged from the converter through a cooler to a filter press for the removal The thus filtered hydrogenated product is then placed in a precipitation tank wherein 0.15% by weight of aqueous oxalic acid is introduced. This precipitation is conducted at a temperature between 50 and 100 1 C., the precipitated copper oxalate removed by filtration and the metal-free hydrogenated prod not then subjected to distillation for the recovery of the alcohols present. The refining by distillation is conducted by pumping the treated and and distilling at a pressure of 10 mm. Hg absolute. Example 2.A sample or" the filtered hydrogenated product obtained by hydrogenating .palmitic acid asdescribed in Example 1', before treating with oxalic acid, contained 300 p. p. rn.

of dissolved metals, mainly copper, and upon refining by the usual distillation procedure at 10 mm. Hg absolute pressure yielded the following Example 3.A sample of the same filtered hydrogenated product as Was used in' Example 2, which contained 300 p. p. m. of dissolved metals, was treated with oxalic acid and filtered. The

dissolvedmetals were reduced to 5 p. p. m. and upon refining by the usual distillation procedure at 10 mm. Hg absolute pressure yielded the following fractions:

I Percent .Lowboilers a 1'7 .Cetyl alcohol 56 Stearyl alcohol 10 1 High boilers l 17 The recovery of cetyl alcohol is increased from -50 to 56% by treatment of the filtered hydrogenated product with oxalic acid which is equivalent to an increase of 12% in the amount of valuable product recovered. In addition, the

quality of the cetyl alcohol recovered in Example .3 is superior to that recovered in Example'z as is evidenced by a higher hydroxyl number, 230 vs.

- 218, and a lower iodine number, 0.5 vs. 4.0.

Example 4.-'-A sample of filtered hydrogenated palmitic acid contained 490 p. p. m. of dissolved metals. After treating with 0.15% of aqueous oxalic acidand filtering, the dissolved metals were reduced to p. p. m. Another portion was treated with 0.15% aqueous oxalic acid but the precipitated metaloxalates were not filtered out.

filtered hydrogenated product into a batch still Refining of these three samples by the usual distillation procedure yielded the following fractions:

As illustrated by the examples, oxalic acid is used. to precipitate the dissolved metals from the crude product, the precipitate being removed by filtration. Other methods of separating the metals present may be employed such, for example, as by electrolysis of the reaction mixture, precipitation with organic or inorganic acids that produce insoluble metal salts in the crude reaction mixture, for example, as carbon dioxide or carbonate salts, or any other suitable method may be used which will separate the metals from this solution down to 50 p. p. m. or less.

When oxalic acid is employed, very small amounts appear to be sufficient to remove copper from the solution. From 0.01 to 0.5% of the oxalic acid, based on the crude hydrogenated oil,

is usually suflicient to precipitate up to about 750 p. p. m of the copper from such a solution. The oxalic acid may be added to the crude hydrogenated oil as such or dissolved in a solvent for the oxalic acid.

After precipitatin the metal salt from the crude oil, the precipitate is separated by filtration and the metal-free hydrogenated oil sub-,

jected'to distillation'under atmospheric or reduced' pressure. It is not necessary to separate the precipitated copper salts prior to distillation, N. B. Example 4. It is often desirable to do so, however, if a highly purified product must be made.

The'process of the'invention is applicable to 'the treatment of fatty acids and their esters generally after hydrogenation for the recovery of the corresponding alcohols. For example, from palrnitic acid, which has been hydrogenated crude oil after hydrogenation and prior to distillation for recovery of the alcohols. After separation, yields were increased to from 5 to 15% above the yields obtained without removal of dissolved copper. The invention is applicable to such hydrogenation processes generally, not only to improve the yields but also to improve the quality of the alcohols produced. We claim:

- 1. In a process for the recovery of long chain aliphatic alcohols from the reaction mixture obtained. by thehydrogenation of compounds of the group consisting .of corresponding long chaincatalyst from the reaction mixture and there-. after precipitating dissolved metals. from the solid catalyst-free reaction mixture from hydrogenation to give less than 50 p. p. m. of dissolved metal prior to recovering the long chain aliphatic alcohols therefrom by distillation.

2. In a process for the recovery of long chain aliphatic alcohols from the crude reaction mixture obtained by the hydrogenation of compounds of the group consisting of corresponding long chain aliphatic acids and their esters by a hydrogenation reaction in which copper chromite is employed as the catalyst, the steps which comprise separating by filtration the solid copper catalyst present from the reaction mixture and thereafter precipitating dissolved copper from the solid catalyst-free mixture from hydrogenation to give; less than 50 p. p. m. of dissolved copper prior to recovering the long chain aliphatic alcohols therefrom by distillation.

3. The process of claim 2 in which the dissolved copper is precipitated with oxalic acid as copper oxalate and the precipitated copper oxalate removed by filtration prior to'recovery of the long chain aliphatic alcohols. V

4. In a process for the recovery of cetyl alcohol from the crude reaction mixture obtained by the hydrogenation of palmitic acid in the presence of copper chromite catalyst at a temperature between 240 C. and 400 C. and under a pressure between 300 and 5000 lbs/sq. inch, the steps between 300 and 5000 lbs/sq. inch, the steps which comprise separating by filtration the solid copper chromite catalyst from the reaction mixture and thereafter precipitating sufficient dissolved copper from the crude mixture from hydrogenation with oxalic acid to'reduce the dissolved copper content to less than 50 p. p. m.'and thereafter recovering the cetyl alcohol by distillation.

6. In a process for the recovery of long chain aliphatic alcohols from the reaction mixture obtained by the hydrogenation of compounds of the group consisting of corresponding long chain aliphatic acids and their esters in the presence of a metal hydrogenation catalyst, the steps which comprise separating the solid catalyst fromthe reaction mixture by filtration and thereafter removing dissolved metals from the solid catalyst-free reaction mixture from hydrogenation to give less than 50 p. p. m. of dissolved metal 7 prior to recovering the long chain aliphatic alcohols therefrom by distillation.

which comprise separating. the solid copper chromite catalyst by filtration from the reaction mixture and thereafter removing sufficient dissolved copper from the crude mixture from hydrogenation to reduce the copper content to less than 50 p. p. m. of dissolved copper and thereafter recovering the cetyl alcohol by distillation.

5. In a process for the recovery of cetyl alcohol from the crude reaction mixture obtained by the hydrogenation of palmitic acid in the presence of 7. In a process for the recovery of cetyl alcohol from the crude reaction mixture obtained by the hydrogenation of palmitic acid in the presence of copper chromite catalyst at a temperature between 240 C. and 400 C. and under a pressure between 300 and 5000 lbs./sq. inch, the steps which comprise separating a major portion of the solid copper chromite catalyst from the reaction mixture by filtration, removing sufiicient dissolved copper from the crude mixture from hydrogenation to reduce the copper content to less than p. p. m. and thereafter recovering the cetyl alcohol by distillation.

- RALPH V. GREEN.

ERNEST P. JENSEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,080,419 Green May 18, 1937 2,109,844 Lazier Mar. 1, 1938 2,158,040 Blumenfeld May 9 1939 2,186,272 Wyler Jan. 9, 1940 2,538,034 Peppel Jan. 16, 1951 copper chromite catalyst at a temperature 'between 240 C. and 400 C. and under a pressure 

1. IN A PROCESS FOR THE RECOVERY OF LONG CHAIN ALIPHATIC ALCOHOLS FROM THE REACTION MIXTURE OBTAINED BY THE HYDROGENATION OF COMPOUNDS OF THE GROUP CONSISTING OF CORRESPONDING LONG CHAIN ALIPHATIC ACIDS AND THEIR ESTERS IN THE PRESENCE OF A METAL HYDROGENATION CATALYST, THE STEPS WHICH COMPRISE SEPARATING BY FILTRATION THE SOLID CATALYST FROM THE REACTION MIXTURE AND THEREAFTER PRECIPITATING DISSOLVED METALS FROM THE SOLID CATALYST-FREE REACTION MIXTURE FROM HYDROGENATION TO GIVE LESS THAN 50 P.P.M. OF DISSOLVED METAL PRIOR TO RECOVERING THE LONG CHAIN ALIPHATIC ALCOHOLS THEREFROM BY DISTILLATION. 